1. Field of the Invention
The present invention relates to an image processing method and apparatus for processing an image in accordance with an attribute of a drawing object, and to a storage medium which stores program codes realizing such a method.
2. Related Background Art
An example of the structure of a conventional image processing apparatus is shown in FIG. 9. Reference numeral 801 represents a printer driver, and reference numeral 802 represents a rasterizer for rasterizing a drawing object generated by an application program and received from a system. Reference numeral 803 represents an image buffer used for configuring a print image of a rasterized drawing object. Reference numeral 804 represents a color conversion unit for converting a logical color of the contents in the image buffer into a physical color to be printed out with a printer. Reference numeral 805 represents a dot pattern coding unit for converting color converted data into a print dot pattern to be printed with the printer and coding the print dot pattern. Reference numeral 806 represents a printer command addition unit for adding a command to the dot pattern code to allow the printer to receive the dot pattern code.
In the apparatus shown in FIG. 9, the printer resolution is sufficiently higher than that of the rasterized image, and each rasterized pixel is expressed by a plurality of print dots. Each pixel can therefore have a broad color expression.
Data generated by various applications are constituted of a plurality of drawing objects in one page. Each object has one of the following attributes:
i) Image; PA1 ii) Graphics; PA1 iii) Text.
In each page, each drawing object is rendered at the same resolution. Means for the rendering (color conversion process, rendering resolution, and dot pattern formation) is designed to balance all object attributes.
The above conventional apparatus has been found, however, unsatisfactory in the following points:
(1) If the whole area of a page is rasterized at a high resolution in order to maintain a high grade of a text, it takes a long time to perform a color conversion process in the rasterizing process, and a use amount of a memory increases.
(2) A density pattern method is known as a method for efficiently utilizing a resolution of a printer. With this method, a plurality of dots are processed by dividing them into groups so that a gradation representation performance can be improved. However, if the rasterizing resolution is lowered, the qualities of graphics and texts are considerably degraded although images are less affected. Specifically, there are two types of drawing objects, one (text, graphics) giving prominence to a resolution and the other giving prominence to a gradation (color representation).